• 한국재료학회지
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• 제16권6호
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• pp.394-399
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• 2006

Ferroelectric $HoMnO_3$ thin films were deposited on the Si(100) substrate at $700^{\circ}C$ for 2 hrs by metalorganic chemical vapor deposition (MOCVD) and post-annealed at 850oC by rapid thermal process (RTP). Electrical properties and crystalline phases of $HoMnO_3$ thin films were investigated as a function of postannealing time. Single phase of hexagonal symmetry with c-axis preferred orientation was obtained from $HoMnO_3$ thin films post-annealed at $850^{\circ}C$ for 5 min, while the c-axis preferred orientation was decreased with the increase of post-annealing time, and the thin films post-annealed at $850^{\circ}C$ for 15 min showed the mixture phases of hexagonal and orthorhombic symmetry. P-E (Polarization-Electric field) hysteresis loop of ferroelectric $HoMnO_3$ thin films was observed only for the single phase of hexagonal symmetry, but that was not observed for the mixture phases of the hexagonal and orthorhombic symmetry, which was discussed with the bond valence of Mn ion of crystalline phase. Leakage current density was dependent on the microstructure of thin films as well as the change of valence of Mn ion.

• 한국결정성장학회지
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• 제9권3호
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• pp.299-302
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• 1999

$La_{2-x}Sr_{x}CuO_{4}$ single-crystalline films were prepared on bulk single crystals of Zn-doped $La_{2-x}Sr_{x}CuO_{4}$ as the substrates by LPE technique using two deferent methods. When prepared using an alumina crucible in normal electrical furnace, the $La_{2-x}Sr_{x}CuO_{4}$ films were contaminated with less than 3 at% aluminum from the alumina crucibles. Aluminum contamination either reduced or completely destroyed the superconductivity of the $La_{2-x}Sr_{x}CuO_{4}$ films, For LPE growth by modified TSFZ method using an infrared heating furnace without crucibles, the $La_{2-x}Sr_{x}CuO_{4}$ films of x=0.11 showed superconducting with $Tc_{onset}=36\;K$, which is 10 K higher than that in the $La_{2-x}Sr_{x}CuO_{4}$ bulk single crystals.

• 조명전기설비학회논문지
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• 제16권3호
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• pp.15-19
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• 2002

본 연구는 직류모터를 이용한 단결정 성장제어 시스템의 개발에 관한 것이다. 수동동작에서 샘플링된 매 시간에서의 변위값들을 일련의 명령어로 변환하여 컴퓨터의 제어 신호로서 직류모친의 위치를 조작하여 동작하도록 하는 것이다. 실제 실험에 있어서 기술상의 문제였던 가스의 정밀조정이 가능하였고 조작이 간편하여 사용상의 편리성을 얻을 수 있었다. 또한 자동 가스 조절용 직류모터의 실시간 모니터링 시스템을 연구, 개발함으로써 제품의 품질을 향상 시 킬 수 있었고, 단결정 제조 설비의 개발 또한 용이 할 것으로 사료된다.

• 설비공학논문집
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• 제27권7호
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• pp.375-379
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• 2015

A proper estimate of solar cell efficiency is of great importance for the feasibility analysis of solar cell power plant development. Since solar cell efficiency depends on temperature, several methods have been introduced to measure it by operating temperature modulation. However, the methods either rely on the external environment or need expensive equipment. In this paper, a thermoelectric module was used to control the operating temperature of crystalline silicon solar cells effectively and precisely over a wide range. The output characteristics of crystalline silicon solar cells in response to operating temperatures from $-5^{\circ}C$ to $100^{\circ}C$ were investigated experimentally. Their efficiencies decreased as the temperature rose, since the decrease in the open circuit voltage and fill factor exceeded the increase in the short circuit current. The maximum power temperature coefficient of the single crystalline solar cell was more sensitive to temperature change than that of the polycrystalline solar cell.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 추계학술대회 논문집
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• pp.275-275
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• 2009

CdTe(331)/Si(211) and CdTe(400)/Si(100) thin films have been grown by MOCVD(metal organic chemical vapor deposition) system for large scale of IFPAs(IR focal plane arrays). We have investigated the effect of various growth parameters on the surface morphology and structural quality. Single crystalline CdTe(331) films were grown by two stage growth method - low temperature buffer layer step and high temperature growth step. In other case, single crystal of CdTe(400) films were grown on a few atomic layer thickness of GaAs which is grown on Si(100) substrate by molecular beam epitaxy. The crystalline quality of the films was analyzed by X-ray diffraction. The surface morphology and crystal structure of CdTe films were characterized by optical microscope.

• 한국결정성장학회지
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• 제14권5호
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• pp.215-219
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• 2004

ZnO 에피박막을 사파이어 기판의 (0001)면 상에 RF magnetron sputtering 법으로 성장하였다. 박막의 성장속도는 약 0.1~0.2$\mu\textrm{m}$/hr 였으며, 기판온도가 $600^{\circ}C$일 때, 약 400~500nm두께의 단결정상의 박막을 성장할 수 있었다. 성장된 단결정상 박막에 대하여 XRD분석과 TEM을 이용하여 박막의 품질과 미세구조를 평가하였다.

• 한국세라믹학회지
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• 제44권3호
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• pp.142-146
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• 2007

High-quality one-dimensional GaN nanorods and nanowires were synthesized on Ni-coated c-plan sapphire substrate using halide vapor-phase epitaxy (HVPE). Their structure and optical properties were investigated by X-ray diffraction, scanning and transmission electron microscopy, and photoluminescence techniques. Full substrate coverage of densely packed, uniform, straight and aligned one-dimensional GaN nanowires with a diameter of 80nm were grown at $700{\sim}900^{\circ}C$. The X-ray diffraction patterns, transmission electron microscopic image, and selective area electron diffraction patterns indicate that the one-dimensional GaN nanostructures are a pure single crystalline and preferentially oriented in the [001] direction. We observed high optical quality of GaN nanowires by photoluminescence analysis.

• 한국세라믹학회지
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• 제30권3호
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• pp.236-242
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• 1993

As the fundamental research on preparation of fine single crystalline ferroxaplana by means of glass-crystallization methods using steel twin-roller, the properties of ferroxplana crystallized from glass were studied. Most of the specimens quenched by twin-roller at about 130$0^{\circ}C$ were glass phase, the crystallization of these glasses underwent multi-steps and ferroxplana phase was only stable in the temperature range of 88$0^{\circ}C$ to 95$0^{\circ}C$. Above 95$0^{\circ}C$ ferroxplana begines to be decomposed in glass. Ferroxplana had such magnetic properties as M8=29emu/g, MHC=166Oe, and Curie Temperature, Tc=610$\pm$5K.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2009년도 추계학술발표논문집
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• pp.633-635
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• 2009

It is a quite quality concerning to control temperature of single crystalline growth as it does when you get most of heat treating products. It is also important factor to control temperature when you make the $Al_2O_3$(single crystalline) used to artificial jewels, glass of watches, heat resistant transparent glasses. Thus, it is a major interest to get the proper temperature in accordance with the time process while you are making mixture of oxygen and hydrogen to have the right temperature. In this paper, we will study of electrical valve positioning system for the gas mixture to improve the quality of products.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 추계학술발표논문집 1부
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• pp.337-340
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• 2010

It is a quite quality concerning to control temperature of single crystalline growth as it does when you get most of heat treating products. It is also important factor to control temperature when you make the Al2O3(single crystalline) used to artificial jewels, glass of watches, heat resistant transparent glasses. Thus, it is a major interest to get the proper temperature in accordance with the time process while you are making mixture of oxygen and hydrogen to have the right temperature. In this paper, we will study of electrical valve positioning system for the gas mixture to improve the quality of products.